PROCESS FOR REMOTE LOX/LIN PRODUCTION BY HPAIR TURBO EXPANSION

Abstract

A process for cryogenic air separation and liquefaction, including purifying and compressing an inlet air stream, thereby producing a compressed inlet air stream, dividing the compressed inlet air stream into an ASU portion and a liquefaction portion, introducing the ASU portion into an air separation unit, thereby producing a gaseous oxygen steam and a gaseous nitrogen stream, and introducing the liquefaction portion, the gaseous oxygen steam and the gaseous nitrogen stream into a liquefaction unit, thereby producing a liquid nitrogen stream and a liquid oxygen stream. Wherein, the air separation unit is located more than 200 meters from the liquefaction unit, and there is no compression driven by external energy within 200 meters of the liquefaction unit.

Claims

1. A process for cryogenic air separation and liquefaction, comprising: purifying and compressing an inlet air stream, thereby producing a compressed inlet air stream, dividing the compressed inlet air stream into an ASU portion and a liquefaction portion, introducing the ASU portion into an air separation unit, thereby producing a gaseous oxygen steam and/or a gaseous nitrogen stream, and introducing the liquefaction portion, the gaseous oxygen stream and the gaseous nitrogen stream into a liquefaction unit, wherein the liquefaction portion is turbo expanded to produce the refrigeration to produce the refrigeration to liquefy the gaseous oxygen and gaseous nitrogen [thereby producing a liquid nitrogen stream and/or a liquid oxygen stream, wherein the air separation unit is located more than 200 meters from the liquefaction unit, and wherein there is no compression driven by external energy within 200 meters of the liquefaction unit which is applied to liquefaction.

2. The process of claim 1, wherein no additional refrigeration energy is within 200 meters of the liquefaction unit.

3. The process of claim 2, wherein the additional refrigeration energy is derived from electrical, steam, and/or hydrocarbon containing gas turbine compressor drives.

4. The process of claim 1, wherein the liquefaction portion is between 30 bara and 100 bara.

5. The process of claim 1, wherein the turboexpanded liquefaction air stream is less than 3 bara.

6. The process of claim 1, wherein the liquefaction expander produces power, and wherein at least a portion of the liquefaction expander power is used to drive an air booster, a gaseous oxygen stream compressor, and/or a gaseous nitrogen stream compressor.

7. The process of claim 1, wherein the liquefaction expander produces power, and wherein the liquefaction expander produces power, and wherein at least a portion of the liquefaction expander power is used to produce electricity in an electrical generator.

8. The process of claim 7, wherein the electrical generator is located within 100 meters of the liquefaction unit.

9. The process of claim 1, wherein the ASU portion has a first flowrate, the liquefaction portion has a second flowrate, and the ratio of the first flowrate to the second flowrate is between 1.0 and 2.0.

10. The process of claim 1, wherein the liquid nitrogen stream has a third flowrate, the liquid oxygen stream has a fourth flowrate, the combined third flowrate and fourth flowrate produces a fifth flowrate, and wherein the ratio of the second flowrate to the fifth flowrate is between 2.0 and 4.0.

11. The process of claim 1, further comprising introducing a natural gas stream into the liquefaction unit, thereby producing a liquefied natural gas stream.

12. The process of claim 1, wherein the ratio of the pressure of the liquefaction portion to the pressure of the ASU portion is between 1.3 and 2.3.

13. The process of claim 1 further comprising a recycle air compressor, wherein at least a portion of the turboexpanded air in the liquefaction unit is re-compressed and mixed with the liquefaction portion to be turboexpanded, wherein the recycle air compressor is located <100 m from liquefaction unit.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0007] For a further understanding of the nature and objects for the present invention, reference should be made to the following detailed description, taken in conjunction with the accompanying drawings, in which like elements are given the same or analogous reference numbers and wherein:

[0008] FIG. 1 is a schematic representation of one embodiment of the present invention.

[0009] FIG. 2 is another schematic representation of one embodiment of the present invention.

[0010] FIG. 3 is another schematic representation of one embodiment of the present invention.

[0011] FIG. 4 is another schematic representation of one embodiment of the present invention.

[0012] FIG. 5 is another schematic representation of one embodiment of the present invention.

ELEMENT NUMBERS

[0013] 101=inlet air stream [0014] 102=front end purification unit [0015] 103=purified inlet air [0016] 104=main air compressor [0017] 105=compressed inlet air stream [0018] 106=ASU portion (of compressed inlet air stream) [0019] 107=liquefaction portion (of compressed inlet air stream) [0020] 108=ASU expander [0021] 109=cooled ASU air stream [0022] 110=ASU [0023] 111=liquefaction expander [0024] 112=cooled liquefaction air stream [0025] 113=liquefaction unit [0026] 114=gaseous nitrogen stream [0027] 115=gaseous oxygen stream [0028] 116=liquid nitrogen stream [0029] 117=liquid nitrogen storage unit [0030] 118=liquid oxygen stream [0031] 119=liquid oxygen storage unit [0032] 201=inlet air booster [0033] 202=gaseous oxygen stream compressor [0034] 203=gaseous nitrogen stream compressor [0035] 204=boosted gaseous oxygen stream [0036] 205=boosted gaseous nitrogen stream [0037] 206=natural gas stream [0038] 207=liquefied natural gas stream [0039] 208=electrical generator [0040] 301=liquefaction portion compressor [0041] 302=further compressed liquefaction portion

DESCRIPTION OF PREFERRED EMBODIMENTS

[0042] Illustrative embodiments of the invention are described below. While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and are herein described in detail. It should be understood, however, that the description herein of specific embodiments is not intended to limit the invention to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

[0043] It will of course be appreciated that in the development of any such actual embodiment, numerous implementation-specific decisions must be made to achieve the developer's specific goals, such as compliance with system-related and business-related constraints, which will vary from one implementation to another. Moreover, it will be appreciated that such a development effort might be complex and time-consuming, but would nevertheless be a routine undertaking for those of ordinary skill in the art having the benefit of this disclosure.

[0044] A new and unforeseen arrangement is proposed wherein there are no power driven compression or refrigeration equipment near (say <100 m) the liquefaction unit. The energy for liquefaction is provided by pressurized dry air from the ASU located >100 m (preferably >500 m) from the liquefaction unit. The same air compressor and booster compressor and purification system used to produce dry air for the O2 and N2 separation and compression (typically between 40 bara to 80 bara) may also be used to produce additional high pressure dry air (40 to 80 bara) to the liquefier. The pressurized dry air to the liquefier is turboexpanded to produce the liquefaction energy without external compression energy. In one embodiment the pressurized air is turboexpanded to preferably <2 bara and vented or recycled.

[0045] Turning to FIG. 1, Inlet air stream 101 enters front end purification unit 102, thereby producing purified inlet air 103. Purified inlet air stream 103 is introduced into main air compressor 104, thereby producing compressed inlet air stream 105. Compressed inlet air stream 105 is split into ASU portion 106 and liquefaction portion 107. ASU portion 106 is introduced into ASU expander 108, thereby producing cooled ASU air stream 108. Cooled ASU air stream 108 is introduced into ASU 110, which produces at least gaseous nitrogen stream (GAN) 114, and gaseous oxygen stream (GOX) 115.

[0046] Liquefaction portion 107 is introduced into liquefaction expander 111, thereby producing cooled liquefaction air stream 112. Cooled liquefaction air stream 112, gaseous nitrogen stream 114, and gaseous oxygen stream 115 enter liquefaction unit 113, thereby producing at least liquid nitrogen stream 116 and liquid oxygen stream 118. Liquid nitrogen stream 116 may be introduced into liquid nitrogen storage unit 117. Liquid oxygen stream 118 may be introduced into liquid oxygen storage unit 119. In one embodiment no addition refrigeration energy is within 200 meters of the liquefaction unit. The addition refrigeration energy may be derived from electrical, steam, and/or hydrocarbon containing gas turbine compressor drives. Liquefaction portion 107 may be between 30 bara and 100 bara. Cooled liquefaction air stream 112 may be less than 3 bara, preferably less than 2 bara. ASU portion 106 has a first flowrate, and liquefaction portion has a second flowrate. The ratio of the first flowrate to the second flowrate is between 1.0 and 2.0, preferably 1.5. Liquid nitrogen stream 116 has a third flowrate, and liquid oxygen stream 118 has a fourth flowrate. The third flowrate plus the fourth flowrate is the fifth flowrate. The ration of the second flowrate to the fifth flowrate is between 2.0 and 4.0, preferably between 2.5 and 3.0. In one embodiment natural gas may be introduced into liquefaction unit 113 and liquefied.

[0047] Turning to FIG. 2, at least a portion of the work produced by liquefaction expander 111 may be used to drive inlet air booster 201. At least a portion of the work produced by liquefaction expander 111 may be used to drive gaseous oxygen stream compressor 202, thereby producing boosted gaseous oxygen stream 204, which is then introduced into liquefaction unit 113. At least a portion of the work produced by liquefaction expander 111 may be used to drive gaseous nitrogen stream compressor 203, thereby producing boosted gaseous nitrogen stream 205, which is then introduced into liquefaction unit 113. At least a portion of the work produced by liquefaction expander 111 may be used to produce electricity E in electrical generator 208 which may be located near (within 100 meters) of liquefaction unit 113. In some embodiments, natural gas stream 206 enters liquefaction unit 113, is liquefied, thus producing liquefied natural gas stream 207.

[0048] Turning to FIG. 3, in one embodiment liquefaction portion compressor 301 provides additional compression to liquefaction portion 107, thereby producing further compressed liquefaction portion 302, which is then introduced into liquefaction expander 111. At least a portion of the turboexpanded air is recycled and mixed with liquefaction portion 107 and recompressed in compressor 301.

[0049] Turning to FIG. 4, in one embodiment, the air pressure of stream 107 (second pressure) to liquefaction unit is a higher pressure than the air pressure of stream 106 (first portion) to the ASU unit. The ratio of the second pressure to the first pressure is between 1.3 and 2.3, preferably between 1.5 and 1.8.

[0050] Turning to FIG. 5, air separation unit 110 may be located at least 200 meters, preferably 500 meters, from liquefaction unit 113.

[0051] It will be understood that many additional changes in the details, materials, steps and arrangement of parts, which have been herein described in order to explain the nature of the invention, may be made by those skilled in the art within the principle and scope of the invention as expressed in the appended claims. Thus, the present invention is not intended to be limited to the specific embodiments in the examples given above.